Irish Moss Problems
Irish moss (Sagina subulata) is a moss-like ground cover that you can use to create a living carpet in your garden. It is a good plant for rock gardens or areas that get some foot traffic. It is not really a moss, but it grows into a tight mound just like many types of moss. Irish moss may have white or pink flowers in the summer. It remains nice and green all winter long.
Full Sun or Shade
While Irish moss really enjoys the sun, if you live in a dry area or get a dry summer, your plants may suffer and dry out. If you know your summers are usually hot, plant Irish Moss in an area that gets partial shade. Don't plant it in full shade or your plant will not thrive. It needs at least a few hours of sun each day to grow well. Keep it watered in hot weather. If it does dry up, it should turn green again when the weather cools.
Irish moss is often preyed upon by aphids. You can easily control the aphids with some beneficial insects like ladybugs and lacewings. They both enjoy feasting on aphids and unlike insecticides, won't affect the rest of the biodiversity of your garden. Slugs also love to feast on the soft green foliage. Set out beer traps or use a slug bait if you don't need to worry about pets or children in the area. Moles may sometimes surface in the middle of your Irish moss. If you can tuck the roots back into the soil and water it, the moss should recover well. If you don't see it right away, the roots will dry out and die, causing empty spots in your coverage.
Crown rot may affect Irish moss if the soil does not drain well or is too heavy. This disease causes the plants to rot where the stems join the roots. It is usually fatal, so prevention is much more effective than treatment after the fact.
In colder climates, Irish moss can freeze back and you may need to replace it in the spring. In temperate areas, it may remain green all winter long.
Weeds and Grass
Irish moss is usually dense enough to discourage weeds and grass, but in the event they manage to get through, it is best to try and remove them by hand as soon as you see them rather than resort to herbicides. Waiting until the weed is established may harm the moss when you remove it.